Bill Winters, the former co-chief executive of JP Morgan’s investment banking division, is understood to have been among senior staff at the bank who made clear their concerns about the risks being taken by the CIO.

Mr Winters and other staff from the investment bank raised their worries, saying the unit did not fully understand the risks it was taking and was not properly managing its positions.
In a further blow on Friday night, JP Morgan’s credit rating was cut one notch by Fitch, while S&P lowered the bank’s outlook to negative from stable.